Drainage channels with energy dissipation structures are designed for drainage basins with large slopes. A drainage channel can be destroyed by strong abrasion and scour erosion in a gully with large slopes. In these cases, the channel cannot be used normally, and post-maintenance costs are high. Additionally, a drainage channel with energy dissipation structures can effectively control the velocity of debris flows and achieve safe discharge in the channel due to the increased roughness of the channel caused by the interactions between a debris flow and the stones used to fill the channel.
The rationale for selecting a roughness coefficient significantly affects the accuracy of debris flow velocity calculations; thus, the roughness coefficient is a key parameter in engineering studies. If the debris flow velocity is too large, then the debris flow may scour or even destroy the drainage channel. Conversely, if the debris flow velocity is too small, then debris flow deposition will occur in the drainage channel, which reduces the flow capacity. Therefore, the debris flow velocity in the drainage channel should be less than the erosion resistance velocity to ensure that the drainage channel does not experience erosion damage. For a drainage channel constructed with concrete or via other masonry methods, the roughness coefficient can be obtained according to the material type, and the debris flow velocity in the drainage channel can be calculated. However, the baseplate of a drainage channel with energy dissipation structures differs from that of a smooth drainage channel; thus, the roughness coefficient cannot be directly determined based on the material type, and the optimal design of this drainage channel is limited.